Conventional articles of footwear generally include an upper and a sole structure. The upper provides a covering for the foot and securely positions the foot relative to the sole structure. The sole structure is secured to a lower surface of the upper and configured so as to be positioned between the foot and the ground when a wearer is standing, walking or running.
It is sometimes desirable to include foam padding in regions of a footwear upper. In some cases, such padding may be added for aesthetic reasons. For example, a shoe designer might wish to include raised portions on a shoe upper to enhance certain lines, to create a certain look, to emulate a product logo, or for other reasons. In other cases, foam padding may be added for functional reasons. As one example thereof, increased padding in certain areas may provide extra impact protection to a wearer foot. As another example, padding may also or alternatively be added to stiffen certain areas and provide increased foot support.
An upper of a completed shoe typically has a shape that approximates the shape of the top and side portions of a human foot. This three-dimensional geometry is relatively complex. Conventionally, several techniques have been used to add foam-padded regions to an upper. In one such technique, a foam pad is created by molding foam onto a piece of a textile material. Foam is not formed on a perimeter portion of that material so as to leave a flange around the foam. The element may then be attached to an upper by stitching or otherwise attaching the flange to other components of that upper. Disadvantages of this technique include the requirement for additional sewing operations.
Another conventional technique involves placing an upper onto a foot-shaped form known as a last. The lasted upper is then placed into a mold that surrounds the lasted upper. A foam-producing chemical mixture is poured into regions of the mold cavity that are adjacent to the exterior surface of the lasted upper. Although this technique can avoid the need to sew foam pads onto the upper, it has other disadvantages. For example, molds used in this technique are relatively complex and expensive to fabricate.